Neural Signaling Molecules – Gastrointestinal System

00:01 So now, let’s talk through all these different neural signalling molecules.

00:04 And it usually helps to set these up as tables.

00:07 And this is one thing that you’ll want start lining through so you can make sure you understand which neurotransmitter does what particular function.

00:17 The first one is acetylcholine.

00:19 This is released by the parasympathetic nervous system.

00:22 And its primary functions are increasing motility, increasing secretion, and increasing blood flow.

00:29 ATP is released by the sympathetic nervous system, causing decreases in blood flow.

00:35 Calcitonin gene-related peptide is released by afferents.

00:39 So these are not from the sympathetic or parasympathetic nerves, but from sensory nerves that release calcitonin gene-related peptide to increase blood flow.

00:48 The next class are enkephalins and enkephalins are released by the enteric nervous system.

00:55 So this the local control and these help to constrict sphincters.

01:00 And what this does is you constrict a sphincter, you prevent the food stuff from moving from one area of the GI system to the next.

01:08 A great example of this is the pyloric sphincter, which is located in between the stomach and the duodenum of the small of the intestine.

01:16 If you have it constricted, you’ll have less food stuff going from the stomach into the small intestine.

01:23 Finally, we have gastric releasing peptide and why this is so important is it’s released by both the parasympathetic nervous system and the enteric nervous system and this increases gastrin secretion.

01:34 And remember gastrin secretion is important for increasing hydrogen ions.

01:41 The other last set of neural signalling molecules we have are norpinephrine released by the sympathetic nervous system.

01:48 This decreases motility, decreases secretion, and decreases blood flow.

01:55 Neuropeptide Y, also decreases motility.

01:58 Substance P is released by sensory afferents primarily, but sometimes as well by the parasympathetic nervous system.

02:05 And that causes increases in blood flow.

02:10 And finally, we have vasoactive intestinal peptide and that increases both motility and blood flow.

02:18 So these are all the different neural signalling molecules.

02:22 You will want to identify both where they come from and what function they have.